Spectrophotometric Determination of Tetracycline by Azo Dye Formation with Diazotised p-Nitroaniline-Application to Pharmaceutical Preparations and Biological Fluids

This paper involves a spectrophotometric method for the determination of trace amounts of tetracycline in aqueous solution. The method is based on the coupling of tetracycline with diazotized p-nitroaniline reagent in basic medium to form a violet mono azo dye that is water soluble, stable and shows maximum absorption at 569 nm. Beers law is obeyed over the concentration range 2 400 g / 25 ml final volume, i.e.,
(0.08 16) ppm with a molar absorptivity of 7.8 104 l.mol-1.cm-1 and sandell sensitivity index of 6.2 10-3 g cm-2. The method is applied to the determination of the compound in serum and urine by standard addition method in vitro and in vivo (serum and urine) and pharmaceutical preparation (tetracycllines ointment).